[pct-l] To waterproof or not to waterproof (ye old sleeping bag) that is thee question.

Chris Martin hopeforgorilla at gmail.com
Wed Feb 26 15:57:56 CST 2014

Hi Paint,

The source of moisture is YOU, and that moisture needs to escape to the
atmosphere. Any attempt to trap it inside your sleeping bag will soak it
with condensation, rendering it uninsulative. This is especially a problem
with down (synthetic deals with getting wet a bit better).

You basically used the mylar blanket as a vapor barrier, which will
temporarily make things warmer, but not for long as condensation builds up.
A truly waterproof coating on the outside of your bag would do essentially
the same thing. (Incidentally, a DWR (durable water repellent) coating
wouldn't make a difference in this case because it doesn't trap vapor.)

Some folks use a vapor barrier INSIDE the sleeping bag for additional
warmth. It was popular back in decades past (see The Complete Walker by
Colin Fletcher), but not really anymore because all that trapped body sweat
makes you stink. You could use a mylar blanket in this fashion for extra
warmth, but you will wake up sweat-soaked.

I can think of much better ways to sleep warmer. Any combination of these
would help:
- Insulative sleeping bag liner
- Breathable bivy bag over your sleeping bag
- Sleep wearing more layers (down puffy jacket!)
- Additional insulation underneath

That last one is a big deal. A lot of folks overlook how much heat the
ground will conduct away from your body. You can sleep in a 0-degree bag
and still get really cold if your sleeping pad doesn't also insulate well.
Adding a closed-cell foam pad underneath your usual sleeping pad can make a
big difference.


On Tue, Feb 25, 2014 at 7:41 PM, Paint Your Wagon <n801yz at hotmail.com>wrote:

> OK,
> Experts, newbies, wannabes, confidantes, pirates, confederates, reprobates,
> miscreants,
> escapees, people of no verifiable income, and all card carrying members in
> good standing-
> What say ye in regards to waterproofing a (my) sleeping bag?
> Pros? Cons?
> Background- last fall while up in the big mountains I carried one of those
> emergency mylar bags (space blanket like)
> that weighed maybe 4 ounces, and when it got really cold I would use it as
> an outer shell,
> but the condensation that formed between the outside of my sleeping bag and
> the inside of the emergency bag was ridiculous.
> My bag would be sopping wet, every single time by morning. On a positive
> note, it was way warmer with the emergency bag than without.
> I would as a matter of routine, lay up somewhere around high noon and dry
> everything out.
> Can I expect my newly waterproofed sleeping bag to act in this same manner
> by trapping condensation inside the bag?
> (Removing patrol cap and scratching head...)
> NOTE: I originally bought the treatment to use on my tent and fly which is
> still going to happen.
> Bag: one each Mountain Hardware synthetic Pinole 20.
> http://www.mountainhardwear.com/Award_10_CL.html
> Solution: one each 17 fl. oz. bottle of NIKWAX Tent & Gear Solarproof
> (waterproofing & UV blocker).
> http://www.nikwax.com/en-us/products/productdetail.php?productid=502&itemid=-1&fabricid=-1
> FWIW: I will be upgrading to a Big Agnes Mystic SL 15 before entering the
> sierras.
> https://www.bigagnes.com/Products/Detail/Bag/MysticSL152014
> Wanna' hijack the thread?
> Wanna' talk about last night, hmmm?
> Something else a little more riveting?
> Go for it!
> <>Paint<>
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